French Pat. No. 2 536 536 discloses a composite material, preferably flexible, comprising a substrate of insulating matter 1, on one face of which is deposited an uninterrupted thin layer 2 of a first conductive or semi-conductive matter coated on at least its face opposite said substrate of insulating matter by a succession of zones 3, separated from one another, and disposed in successive rows, constituted by very thin deposits of a second conductive or semi-conductive matter having a different thermoelectric power from that of the first conductive or semi-conductive matter. According to a preferred feature described in this document, at least one channel 4 passes right through each zone 3 and the subjacent thin layer 2, these channels being offset with respect to the centre of each zone traversed advantageously in the same direction, said channels being able to be internally coated with a deposit 7 of the second matter. According to another preferred feature, the uninterrupted layer has the form of an advantageously meandering strip in order to be bendable to form a rectangular or square structure (cf. claims 3 and 4).
In this way, several hundred of elementary thermocouples are obtained, this composite material then constituting a thermic fluxmeter. According to another variant, object of FIGS. 5 and 6, the zones composed of the second matter may be made on each of the faces of the uninterrupted thin layer 2.
The process for preparing such a composite material is described more particularly on page 6, lines 5 to 33 and includes the gluing of a sheet of Constantan on a support formed by a plate 1 of plastics material, followed by the attack by the conventional technique of engraving used for manufacturing printed circuits, of the sheet of Constantan along parallel lines 6 forming two imbricated combs so as to define an uninterrupted thin layer in the form of a meandering strip 2a. On this meandering strip 2a there is deposited by electrolysis layers 3a of copper some microns thick after having protected, by means of a layer of photosensitive resin, the portions which are not to be copper-plated, so as to define the zones 3 mentioned above. One then proceeds with an engraving of holes 4a by chemical attack, these holes then being internally coated with a layer 7 composed of the second conductive or semi-conductive matter, particularly copper.
Finally, the upper face of the device may be coated with a layer 5 of thermosetting resin protecting the copper and the Constantan from oxidation.
Japanese Pat. No. 58 10875 to TOSHIBA further discloses a process for manufacturing sheet-shaped thermocouples. The structure of these thermocouples comprises a support film made of heat-resistant resin, for example a film of polyimide resin, of which one surface is coated with a layer of copper, whilst the opposite surface is coated with a layer of Constantan, the two metal layers then being subjected to etching so as to leave the conducting wire part.
Through holes are then made through the end parts of the two conductor parts and copper is plated on the inside of the orifice, so as to connect the conductor wire parts comprising copper and Constantan.
U.S. Pat. No. 3,554,815 to DU PONT DE NEMOURS also describes a thermopile based on the combination of individual thermocouples disposed on either side of a heat-resistant insulating substrate and connected together by through orifices 11 which are then filled with solder. The shape of the thermocouples is obtained by plating procedures and photoengraving techniques.
The thermocouples are mounted in series. As support material, mention is made of plates of glass-fiber reinforced epoxy resin, laminates of such plates, plates of glass-fiber reinforced, unsaturated polyester resin, laminates of such plates, a laminated plate of phenolic resin-paper and the like.
It is thus observed that, in accordance with the heretofore known devices, they are either constituted by composite materials forming fluxmeter, or by composite materials including one or more thermocouples forming temperature detecting devices.
Where it is desired to measure the thermal flux and to measure the temperature, which is usually necessary, distinct devices should be used, which are therefore inserted at different places, which may lead to corrections of measurement.
It is therefore an object of the present invention to solve the new technical problem of providing a composite material made so as to constitute a measuring device forming a fluxmeter and a temperature sensor combined, with the result that the insertion of a single device enables the thermal flux and the temperature to be measured.
It is also an object of the present invention to solve the new technical problem of providing a composite material made so as to allow the detection of the thermal flux and of the temperature in the same plane.
These technical problems are satisfactorily solved for the first time by the present invention.